By Pete Hall

Jose Mourinho will be without several key Manchester United players for Saturday's Premier League clash with Southampton at Old Trafford (kick-off 5.30pm).

After dropping more points at home to Burnley on Boxing Day, United find themselves 15 points behind rivals Manchester City - the biggest points gap between first and second place after 20 games in English top-flight history.

Two wins in their last five games has also opened the door for the chasing pack, with Chelsea now just a point behind in third.

Manchester United boss Jose Mourinho says he is unable to rest a 'tired' Romelu Lukaku because of his lack of attacking options

Manchester United boss Jose Mourinho says he is unable to rest a 'tired' Romelu Lukaku because of his lack of attacking options

The temptation to rest out-of-form Romelu Lukaku has not crossed Mourinho's mind, though. Mourinho said his striker, who has played every single minute of United's 20 Premier League games, is "tired" having scored just four times in 19 games, yet he feels he cannot give him a rest.

"The guy [Lukaku] is fantastic for me and for the team," Mourinho said. "He gives absolutely everything and I have no criticism. Can I give him a rest? No, I can't."

Southampton have lost four of their last seven Premier League matches, failing to produce a win since late November, and were brushed aside by Tottenham with ease on Boxing Day.

Southampton manager Mauricio Pellegrino says it was the right time to let Virgil van Dijk leave and wants the board to reinvest in the squad

Southampton manager Mauricio Pellegrino says it was the right time to let Virgil van Dijk leave and wants the board to reinvest in the squad

"I was analysing that game [Tottenham] but I think now our target is to bounce back in the Southampton way, to play with more character and be more clinical in ways," manager Mauricio Pellegrino said.

Team news

Anthony Martial and Matteo Darmian both returned to training on Thursday but remain doubtful with the knocks that kept them out against Burnley, while Chris Smalling and Antonio Valencia are also unlikely to feature. Michael Carrick, Marouane Fellaini and Eric Bailly are all out.

Southampton defender Virgil van Dijk will join Liverpool on January 1, so will not feature. Charlie Austin is unavailable as he must serve the second of his three-match ban for violent conduct and the forward is also affected by a significant hamstring injury.

Virgil van Dijk has played his last game for Southampton

Ryan Bertrand (hamstring) faces a late fitness test, but Cedric Soares (ankle) will not feature for Pellegrino's side.

Opta stats

The Red Devils have kept a clean sheet in each of their last three Premier League games against Southampton, after a run of nine games without one

Southampton have won two of their last three league visits to Old Trafford, after a run of 19 games without a win there (D3 L16). Indeed, their last two away wins against Man Utd came over a period of 35 games

United won the reverse fixture thanks to a Romelu Lukaku goal - they've not beaten Southampton home and away in the same season since 2012-13

Zlatan Ibrahimovic has scored four goals in his two games against Southampton in all competitions

Watch a preview of Saturday's Premier League fixtures including Chelsea against Stoke, Southampton's trip to Man Utd and Liverpool v Leicester

Watch a preview of Saturday's Premier League fixtures including Chelsea against Stoke, Southampton's trip to Man Utd and Liverpool v Leicester

Merson's prediction

Southampton were atrocious at Spurs, and Man Utd weren't great either against Burnley. Man Utd should be blowing teams away, and I still think it will happen at some point.

Saints are all over the place, and I didn't see too many of their players playing for Mauricio Pellegrino at Wembley, which is very worrying. There are ways of losing football matches, and the way they lost against Spurs was not good at all. I'd be worried coming into this game. If they are battered again, I think Pellegrino could go.

For Man Utd, I cannot remember in 90 minutes Romelu Lukaku having a chance against Burnley, and that's with the vast majority of the ball and being in Burnley's half for the entire second period. I think that's a problem with both Lukaku and the creativity of the side. But if they can't blow these away, there will be some unrest at Old Trafford.